ROHR Simulation for DI Diesel Engines Based on Sequential Combustion Mechanisms

In this paper a zero-dimensional simulation methodology for efficient pre-optimization of the combustion process in DI diesel engines is presented. A new model for the calculation of the rate of heat release is unveiled. It is based on the separate description of both the primary processes closely related to the fuel jet as well as the following combustion of the fuel mass remaining after the end of injection.

The modeling of fuel mass distribution between premixed and diffusion combustion as well as a model for the fuel preparation time are explained. Furthermore, models for the calculation of ignition delay and premixed combustion based on an extended Arrhenius formulation are discussed, as well as turbulent combustion on the basis of a Magnussen model.

The new features of the heat release model prove to be necessary to describe the effects of modern high-pressure fuel injection systems on the combustion process regarding the strong influence of the injection rate on the burn rate.